1. Studies on a preparation of a high purity sodium chloride by ion exchange resin were performed in the following point,
(1) Change of height and colour of the resin layer
(2) Change of pH value and concentration of the elution
(3) Distribution state of the impurities that were absorbed in the resin layer
As the result of the above experiments, 31 of the initial elution per about 500cc of resin should be removed and watching the cutting point by conductometer about 80 1 of the purified sodium chloride solution was produced.
2. After the sodium chloride crystal was separated by the special centrifuge, it was dried preliminary in the electric oven at 50-80°C, and the crystal was transported into the Pt-dish and was heated at 650°C for 8 hrs. in the electric furnace.
This method was excellent, especially no contamination of impurities and no solidification of crystal.

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The behaviors of copper, zinc, lead, iron, aluminum, manganese and molybdenum in the process of salt making in 5 representative plants of Japan were traced through the analysis of the various samples obtained from the plants, and following results were obtained.
1. The distribution tendency of these metals coincided with the results already reported in part 1 of these studies.
2. Among these metals, molybdenum was the only metal which was derived from sea water. The other metals entered mainly as suspended matter in raw materials, or originated from the salt field or the apparatus.
3. Copper entered mainly from the tube of the preheater or evaporator, and zinc was derived mainly from the zinc plate used for the cathodic protection of evaporators.
Greater parts of both these metals were concentrated in the bittern.
4. Molybdenum was concentrated mostly, and lead and iron partly, in the bittern.
A presumption was made on the behavior of 12 minor metals in a salt field through comparison of the results of the analysis of solar salt and that of shallow water mud.
In solar salt, iron, aluminum, titanium, cobalt, chromium, nickel, molybdenum and perhaps vanadium entered as mud itself, and copper, zinc, lead and manganese were derived mainly through dissolution of these metals from the mud of salt field.

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The NS salt B prepared from bittern can be used without any treatment as a new basic potassium magnesium fertilizer. It may, also, be used to prepare potassium sulfate by hydrolysis. So, the following procedures to separate potassium sulfate were investigated:(1) hydrolysis of NS salt B into the solid magnesium hydroxide and the solution containing one part of potassium sulfate and two parts of magnesium sulfate,(2) addition of gypsum to the hydrolized solution to separate syngenite,(3) hydrolysis of syngenite, into the solid gypsum and the solution containing potassium sulfate and small amount of calcium sulfate,(4) crystallization of potassium sulfate by evaporating the solution obtained in the third step,(5) utilization of the separated mother liquor of syngenite in the second step.

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Recently, the cathodic protection which is one of the corrosion protection methods has generally been applied to iron and steel installations, however there have been few applications to pumps.
Cathodic protection of a centrifugal pump for sea water by zinc anodes has been investigated.
The results obtained are as follows.
(1) The corrosion of centrifugal pump is prevented completely by the cathodic protection by selecting suitable numbers and positions of zinc anodes.
(2) The necessary current for achieving complete protection is 500-600mA per square meter of steel surface. This current density is about four times of the value which is generally accepted for protecting steel in moving sea water.

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The uranium contents of sea water, brine and bittern were determined fluorophotometrically by fusion method after extraction with ethylacetate.
Sample solution was filtered by membrane filters (average pore, size, 0.4μ).
Uranium contents of both soluble and particulated parts were determined.
The range of uranium contents dissolved in sea water, brine and bittern were from 1.4 to 2.5μg/L (average 1.8), from 6.0 to 150.8μg/L (average 29.7), from 52.8 to 154.4/μg/I.,(average88.6) respectively, and these values showed that the uranium in sea water was concentrated in bittern remarkably.
Uranium contents in particulated matter in bittern varied from 24.5 to 59.2μg/L (average 39.7) and these values were found to be about 1/2-1/3 of the total uranium contents.

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